SURVIVAL TIME OF CIRCULATING LONG-ACTING THYROID STIMULATOR IN NEONATAL THYROTOXICOSIS: IMPLICATIONS FOR DIAGNOSIS AND THERAPY OF THE DISORDER

Abstract

We have described an infant with neonatal thyrotoxicosis who developed supraventricular tachycandia, goiter, and periorbital edema. Both the baby's and mother's sera contained the long-acting thyroid stimulator (LATS). While the level of LATS remained unchanged in the serum of the mother, it rapidly fell in the serum of the infant. The biological half-life of LATS in the infant's serum was calculated to be 6 days, and by the age of 21 days no LATS activity could be detected. Based on these findings, antithyroidal treatment which had been instituted soon after birth was discontinued on the thirty-eighth day without recurrence of signs or symptoms of thyrotoxicosis. In addition to conventional antithyroid therapy for thyrotoxicosis, exchange transfusion and prenatal corticosteroid therapy of the mother may be considered when neonatal or maternal serum LATS titers, respectively, are very high.